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Abstract:

A variable capacitor is provided for use with an electronic circuit board
including a first terminal portion and a second terminal portion, to be
built in a position indicator. The variable capacitor includes a
dielectric having a first surface portion and a second surface portion
opposite to the first surface portion, and a conductive elastic member
having a board coupling portion and a dielectric contacting portion. The
first terminal portion is coupled to the first surface portion, the
second terminal portion is coupled to the board coupling portion, and the
dielectric contacting portion is disposed separately from the second
surface portion so as to face the second surface portion and is
configured to be deformed to come in contact with the second surface
portion of the dielectric. The variable capacitor is configured such that
a contact area between the second surface portion and the dielectric
contacting portion is changed in correspondence to a depressing force,
which is applied against the dielectric contacting portion in a direction
toward the dielectric, thereby changing an electrostatic capacitance of
the variable capacitor.

Claims:

1. A variable capacitor for use in conjunction with an electronic circuit
board including a first terminal portion and a second terminal portion,
said variable capacitor comprising: a dielectric having a first surface
portion and a second surface portion opposite to said first surface
portion; and a conductive elastic member having a board coupling portion
and a dielectric contacting portion, wherein said first terminal portion
is coupled to said first surface portion, said second terminal portion is
coupled to said board coupling portion, and said dielectric contacting
portion is disposed separately from said second surface portion so as to
face said second surface portion and is configured to be deformed to come
in contact with said second surface portion, and a contact area between
said second surface portion and said dielectric contacting portion is
changed in correspondence to a depressing force, which is applied against
said dielectric contacting portion in a direction toward the dielectric,
thereby changing an electrostatic capacitance of the variable capacitor.

2. The variable capacitor according to claim 1, further comprising a
spacer configured to provide a space between said second surface portion
and said dielectric contacting portion when the depressing force is not
applied.

3. The variable capacitor according to claim 2, wherein said conductive
elastic member includes an accommodating portion configured to
accommodate said dielectric and said spacer in the accommodating portion.

4. The variable capacitor according to claim 3, wherein a distance from a
center to an outer periphery of said spacer is longer than a distance
from a center to an outer periphery of said second surface portion, and
is shorter than a distance from a center to an outer periphery of said
accommodating portion.

5. The variable capacitor according to claim 1, wherein said electronic
circuit board includes a cutout portion adjacent to said first terminal
portion, and wherein said cutout portion is fixed to said dielectric with
a conductive adhesive.

6. The variable capacitor according to claim 1, wherein the board
coupling portion of said conductive elastic member comprises a groove
configured to receive a portion of the electronic circuit board therein.

7. The variable capacitor according to claim 1, wherein said conductive
elastic member includes an accommodating portion, which is configured to
accommodate said dielectric in the accommodating portion and is further
configured to provide a space between said second surface portion of the
dielectric and said dielectric contacting portion when the depressing
force is not applied.

8. The variable capacitor according to claim 7, further comprising an
insulator portion applied on a bottom surface of the accommodating
portion.

9. A position indicator, comprising: an electronic circuit board
including a first terminal portion and a second terminal portion, a
variable capacitor used in conjunction with the electronic circuit board,
said variable capacitor including: a dielectric having a first surface
portion and a second surface portion opposite to said first surface
portion, and a conductive elastic member having a board coupling portion
and a dielectric contacting portion, wherein said first terminal portion
is coupled to said first surface portion, said second terminal portion is
coupled to said board coupling portion, and said dielectric contacting
portion is disposed separately from said second surface portion so as to
face said second surface portion and is configured to be deformed to come
in contact with said second surface portion, and a contact area between
said second surface portion and said dielectric contacting portion is
changed in correspondence to a depressing force, which is applied against
said dielectric contacting portion in a direction toward the dielectric,
thereby changing an electrostatic capacitance of the variable capacitor;
and a resonance circuit having said variable capacitor.

10. The position indicator according to claim 9, further comprising a
case and a core body, wherein said electronic circuit board, said
variable capacitor, said resonance circuit, and said core body are all
accommodated in said case, such that one end of said core body protrudes
from said case for indicating a position and another end of said core
body is provided to depress said dielectric contacting portion of the
conductive elastic member toward said second surface portion of the
dielectric when the depressing force is applied.

11. The position indicator according to claim 10, further comprising a
core body coupling portion configured to couple said core body to said
variable capacitor.

12. The position indicator according to claim 10, wherein the conductive
elastic member further includes a core body coupling portion configured
to coupled said core body to said variable capacitor.

13. The position indicator according to claim 12, wherein said core body
coupling portion defines a hole configured to receive the other end of
said core body provided to depress said dielectric contacting portion.

14. The position indicator according to claim 12, further comprising a
connection cap provided between said core body coupling portion and the
other end of said core body provided to depress said dielectric
contacting portion.

15. An input device, comprising: a position indicator including a case,
an elongated core body accommodated within the case and having one end
thereof protruding from said case while having another end thereof
accommodated within the case, a variable capacitor whose electrical
capacitance changes when an external force is applied thereto through the
other end of said core body, and an electronic circuit board having a
first terminal portion and a second terminal portion coupled to the
variable capacitor; and a position detector comprising a detection
surface configured to detect a position indicated by said one end of the
core body protruding from said case, wherein said variable capacitor of
said position indicator includes a dielectric having a first surface
portion and a second surface portion opposite to said first surface
portion, and a conductive elastic member having a board coupling portion
and a dielectric counting portion, said first terminal portion is coupled
to said first surface portion, said second terminal portion is coupled to
said board coupling portion, and said dielectric contacting portion is
disposed separately from said second surface portion so as to face said
second surface portion and is configured to be deformed to come in
contact with said second surface portion, and a contact area between said
second surface portion and said dielectric contacting portion is changed
in correspondence to a depressing force, which is applied against said
dielectric contacting portion in a direction toward the dielectric
through the other end of said core body, thereby changing an
electrostatic capacitance of the variable capacitor.

16. The input device according to claim 15, wherein said position
indicator includes a resonance circuit composed of a coil and said
variable capacitor, said resonance circuit changes a resonance frequency
in accordance with a change in electrical capacitance of the variable
capacitor based on an external force applied thereto through said core
body, and said position detector detects the change in resonance
frequency as a pen pressure.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority under 35 U.S.C. 119(a) of
Japanese Application No. 2010-215621, filed Sep. 27, 2010, the entire
content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a variable capacitor whose
capacitance value is changed in accordance with a pressure or a
displacement applied thereto from the outside, a position indicator using
the variable capacitance, and an input device using the position
indicator.

[0004] 2. Description of the Related Art

[0005] In recent years, an input device has been used with a personal
computer and the like. The input device is composed, for example, of a
position indicator and a position detector. In this case, the position
indicator is formed as of a pen type. The position detector has an input
surface to which a pointing operation, characters, figures and the like
are inputted by using the position indicator.

[0006] A variable capacitor as described in Japanese Patent Laid-Open No.
Hei 4-96212 (hereinafter referred to as Patent Document 1) has been used
in a pen-pressure detecting portion of the position indicator. The
variable capacitor as described in Patent Document 1 includes a first
electrode and a second electrode. The first electrode is mounted to one
surface of a dielectric. The second electrode is disposed on the other
surface of the dielectric and has flexibility. The variable capacitor
includes a section for separating the second electrode and the other
surface of the dielectric by a small space, except for a portion of the
second electrode and the other surface of the dielectric, and a section
for applying a relative pressure or displacement between the second
electrode and the dielectric.

[0007] FIGS. 21A and 21B are schematic views each showing a concrete
construction of a conventional variable capacitor. FIG. 21A is a
schematic view showing an initial state in the conventional variable
capacitor, and FIG. 21B is a schematic view showing a state in which a
pressure is applied to the conventional variable capacitor.

[0008] The variable capacitor 200 includes a dielectric 201 having
approximately a disc-like shape, a first electrode 202, and a second
electrode 203. In this case, the first electrode 202 is mounted on one
surface 201a of the dielectric 201. The second electrode 203 is disposed
on the other surface 201b opposite to the one surface 201a of the
dielectric 201. The second electrode 203 has flexibility and is disposed
on the other surface 201b of the dielectric 201 through a ring-like
spacer 204. In addition, a rod-like core body 210 is provided on a side
of the second electrode 203 opposite to the dielectric 201 side through
an elastic body 205.

[0009] A first terminal 206 is provided on the one surface side of the
first electrode 202. The first terminal 206 is composed of a disc-like
flange portion 206a, and a lead portion 206b extending approximately from
a center of one surface of the disc-like flange portion 206a. When a pen
pressure is applied to the variable capacitor 200, the flange portion
206a comes in contact with one surface of the first electrode 202 to be
electrically connected to the first electrode 202.

[0010] A second terminal 207 is provided in an end (edge) portion of the
second electrode 203. The second terminal 207 is composed of a disc-like
flange portion 207a and a lead portion 207b extending approximately from
a center of one surface of the flange portion 207a similarly to the case
of the first terminal 206. When the pen pressure is applied to the
variable capacitor 200, the flange portion 207a is in contact with an end
portion of one surface of the second electrode 203 and is electrically
connected to the first electrode 203.

[0011] In the variable capacitor 200, in a state in which neither the
pressure nor the displacement is applied to the core body 210 (initial
state), a small space is defined between the other surface 201b of the
dielectric 201 and the second electrode 203 by a spacer 204. As shown in
FIG. 21B, when the pressure is applied to the core body 210, both of the
elastic body 205 and the second electrode 203 are depressed by the core
body 210 to be elastically deformed. As a result, the second electrode
203 comes in contact with the other surface 201b of the dielectric 201.
When a contact area between the second electrode 203 and the other
surface 201b of the dielectric 201 is increased, a value of an electrical
capacitance defined between the first and second terminals 206 and 207 is
increased. As a result, a change in value of the electrical capacitance
defined between the first and second terminals 206 and 207 is detected,
thereby detecting the pressure (pen pressure) applied to the core body
210.

SUMMARY OF THE INVENTION

[0012] The conventional variable capacitor 200 described with reference to
FIGS. 21A and 21B is actually formed within a housing member.
Specifically, with respect to assembly of the variable capacitor 200, as
shown in FIG. 22, the dielectric 201 having the first electrode 202
provided thereon, the spacer 204, the second electrode 203, and the
elastic body 205 are laminated in this order to be formed within the
housing member 221.

[0013] In this case, the first terminal 206 is connected to the first
electrode 202, and the second terminal 207 is connected to the end (edge)
portion of the second electrode 203. Also, both of a cap body 72 for
holding the core body 210 and a second housing member 222 are inserted
from a lower side of the first housing member 221 into the first housing
member 221, thereby forming one variable capacitor 200.

[0014] Therefore, the conventional variable capacitor 200 is formed from
the nine parts or components: (1) the first terminal 206; (2) the second
terminal 207; (3) the first housing member 221; (4) the dielectric 201
having the first electrode 202 provided thereon; (5) the spacer 204; (6)
the second electrode 203; (7) the elastic body 205; (8) the cap body 72
for holding the core body 210; and (9) the second housing member 222.

[0015] As described above, there are a large number of parts or components
in the conventional variable capacitor 200. In addition, the size of the
conventional variable capacitor 200 is relatively small because the
conventional variable capacitor 200 is accommodated in a pen-type
position indicator. For this reason, it is rather difficult and
time-consuming to manufacture the conventional variable capacitor 200 in
some cases.

[0016] In light of the foregoing, according to one aspect of the present
invention, a variable capacitor is provided which is simpler to
construct, without having its performance compromised. Further, a
position indicator using such variable capacitor, and an input device
including such position indicator are provided.

[0017] According to an embodiment of the present invention, a variable
capacitor is provided for use with an electronic circuit board including
a first terminal portion and a second terminal portion, which are all to
be built in a position indicator. The variable capacitor includes a
dielectric having a first surface portion and a second surface portion
opposite to said first surface portion, and a conductive elastic member
having a board coupling portion and a dielectric contacting portion. The
first terminal portion is coupled to the first surface portion, the
second terminal portion is coupled to the board coupling portion, and the
dielectric contacting portion is disposed separately from the second
surface portion so as to face the second surface portion and is further
configured to be deformed to come in contact with the second surface
portion of the dielectric. A contact area between the second surface
portion and the dielectric contacting portion is changed in
correspondence to a depressing force, which is applied against the
dielectric contacting portion in a direction toward the dielectric,
thereby changing an electrostatic capacitance of the variable capacitor.

[0018] In the variable capacitor described above, the first terminal
portion of the electronic circuit board is coupled to the first surface
portion of the dielectric, and the second terminal portion of the
electronic circuit board is coupled to the board coupling portion of the
conductive elastic member. The dielectric contacting portion of the
conductive elastic member is disposed separately (spaced) from the second
surface portion of the dielectric so as to face the second surface
portion of the dielectric, but is configured to be deformed toward the
second surface portion when a depressing force is applied. In other
words, the dielectric contacting portion and the second surface portion
of the dielectric come in contact with each other when the depressing
force is applied. The contact area between the dielectric contacting
portion and the second surface portion of the dielectric is changed,
thereby changing the electrostatic capacitance of the variable capacitor.

[0019] Therefore, when a depressing force is applied, a connection system
is formed as follows: the first terminal portion of the electronic
circuit board→the first surface portion of the
dielectric→the second surface portion of the dielectric→the
dielectric contacting portion of the conductive elastic member→the
board coupling portion of the conductive elastic member→the second
terminal portion of the electronic circuit board. In the connection
system, the variable capacitor is provided whose electrical capacitance
changes in accordance with the contact state, corresponding to the
depressing force, between the second surface portion of the dielectric
and the dielectric contacting portion of the conductive elastic member.

[0020] As a result, a variable capacitor is provided, which has a very
simple construction including two members: the dielectric and the
conductive elastic member. In addition, the performance of the variable
capacitor is not degraded as compared with that of a conventional
variable capacitor. In other words, it is possible to realize a variable
capacitor, which is simpler to construct and yet maintains high
performance.

[0021] According to another embodiment of the present invention, a
position indicator is provided including the variable capacitor as
described above, an electronic circuit board having electronic circuit
provided therein, and a resonance circuit having the variable capacitor
as its element.

[0022] Therefore, it is possible to realize a position indicator using the
variable capacitor, which is simpler to construct and maintains high
performance.

[0023] According to still another embodiment of the present invention, an
input device is provided including a position indicator and a position
detector having a detection surface configured to detect a position
indicated by the position indicator. The position indicator includes a
case, an elongated core body accommodated within the case and having one
end thereof protruding from the case while having another end thereof
accommodated within the case, a variable capacitor whose electrical
capacitance changes when an external force is applied thereto through the
core body, and an electronic circuit board having a first terminal
portion and a second terminal portion. The variable capacitor of the
position indicator includes a dielectric having a first surface portion
and a second surface portion opposite to the first surface portion, and a
conductive elastic member having a board coupling portion and a
dielectric contacting portion. The first terminal portion is coupled to
the first surface portion, the second terminal portion is coupled to the
board coupling portion, and the dielectric contacting portion is disposed
separately from the second surface portion so as to face the second
surface portion and is configured to be deformed to come in contact with
said second surface portion. A contact area between the second surface
portion and the dielectric contacting portion is changed in
correspondence to a depressing force, which is applied against the
dielectric contacting portion in a direction toward the dielectric,
thereby changing an electrostatic capacitance of the variable capacitor.

[0024] Therefore, it is possible to realize an input device using the
position indicator of the present invention.

[0025] As set forth hereinabove, according to various embodiments of the
present invention, it is possible to realize a variable capacitor which
is simpler to construct and maintains high performance. In addition, it
is possible to realize a position indicator using the variable capacitor,
and an input device using such position indicator including the variable
capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a perspective view showing a construction of an
embodiment of an input device according to the present invention;

[0027] FIG. 2 is a cross sectional view taken along line A-A' of a
position indicator shown in FIG. 1;

[0028] FIG. 3 is an exploded perspective view of a variable capacitor in
the embodiment of the input device shown in FIG. 1;

[0029] FIGS. 4A and 4B are a top plan view and a bottom plan view,
respectively, of a conductive elastic member of the variable capacitor
shown in FIG. 3;

[0030] FIG. 5 is a cross sectional view of the variable capacitor portion
when both of a printed wiring board and a core body are mounted;

[0031] FIGS. 6A and 6B are cross sectional views explaining an example of
joining between a printed wiring board and a dielectric;

[0033] FIG. 8 is a block diagram, partly in circuit, showing a position
indicator and a position detector composing the input device according to
an embodiment of the present invention;

[0034] FIG. 9 is a flow chart showing processing executed by a processing
portion of the position detector composing the input device according to
an embodiment of the present invention;

[0035] FIGS. 10A to 10D are waveform charts respectively showing waveforms
obtained in different portions, in an X-axis global scanning operation
carried out by the position detector composing the input device according
to an embodiment of the present invention;

[0036] FIGS. 11A to 11D are waveform charts respectively showing waveforms
obtained in different portions, in a Y-axis global scanning operation
carried out by the position detector composing the input device according
to an embodiment of the present invention;

[0037] FIGS. 12A to 12D are waveform charts respectively showing waveforms
obtained in different portions, in an X-axis sector scanning operation
and a Y-axis sector scanning operation carried out by the position
detector composing the input device according to an embodiment of the
present invention;

[0038] FIG. 13 is a circuit diagram showing another configuration of a
resonance circuit provided in the position detector composing the input
device according to an embodiment of the present invention;

[0039] FIG. 14 is a circuit diagram showing another configuration of the
position detector composing the input device according to an embodiment
of the present invention;

[0040] FIGS. 15A and 15B are a cross sectional view showing another
construction of the variable capacitor, and a top plan view showing a
construction of a conductive elastic portion shown in FIG. 15A,
respectively;

[0041] FIG. 16 is a cross sectional view showing still another
construction of the variable capacitor;

[0042] FIG. 17 is a cross sectional view showing yet another construction
of the variable capacitor;

[0043] FIGS. 18A and 18B are a top plan view and a bottom plan view,
respectively, each showing another construction of the conductive elastic
member;

[0044] FIGS. 19A and 19B are a top plan view and a transverse cross
sectional view, respectively, showing still another construction of the
conductive elastic member;

[0046] FIGS. 21A and 21B are an explanatory view schematically showing an
initial state of a conventional variable capacitor, and an explanatory
view showing a state in which a pressure (pen pressure) is applied to a
core body of the conventional variable capacitor, respectively; and

[0047]FIG. 22 is an exploded perspective view showing a concrete
construction of the conventional variable capacitor shown in FIGS. 21A
and 21B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] The preferred embodiments of the present invention will be
described in detail hereinafter with reference to the accompanying
drawings. It is noted that members common to the figures are designated
by the same reference numerals or symbols, respectively. In an embodiment
which will be described below, an accommodating portion claimed in the
appended claims is embodied as a holding hole 15ch for a board and the
like. A board coupling portion claimed in the appended claims is embodied
as a groove portion 15ck provided in a holder portion 15c1 for a board
and the like in one embodiment. Also, a core coupling portion claimed in
the appended claims is embodied as a core body holding hole 15cp and a
core body holder 15c2 in one embodiment. It should be noted that the
present invention is by no means limited to one of these embodiments
which will be described below.

[Input Device]

[0049] Firstly, a schematic construction of an embodiment of the input
device according to the present invention will be described with
reference to FIG. 1. FIG. 1 is a perspective view showing the schematic
construction of the embodiment of the input device according to the
present invention.

[0050] The input device 10 is composed of a position detector 1, and a
position indicator 2 for inputting information to the position detector
1.

[Position Detector 1]

[0051] The position detector 1 is connected to an external apparatus such
as a personal computer or a Personal Digital Assistant (PDA) via a cable
8, whereby the position detector 1 is used as an input device for such an
external apparatus. It is noted that although not specifically
illustrated, such a position detector 1 may be built in the personal
computer or the like.

[0052] The position detector 1 is composed of a detecting portion 4 and a
chassis 5. In this case, the detecting portion 4 detects a position
indicated by the position indicator 2, which will be described later. The
chassis 5 forms approximately a hollow thin rectangular parallelepiped
and has the detecting portion 4. The chassis 5 has an upper chassis 7 and
a lower chassis (not shown). In this case, the upper chassis 7 has an
opening portion 6 for exposing a detection surface of the detecting
portion 4. The upper chassis 7 is superposed on the lower chassis (not
shown). The detecting portion 4 is fitted into the quadrangular opening
portion 6 of the upper chassis 7, so that the input surface of the
detecting portion 4 is exposed through the quadrangular opening portion
6. The position detector 1 having such a construction receives an input
of characters, figures or the like, made by a pointing operation of the
position indicator 2, which will be described below.

[Position Indicator 2]

[0053] Next, a description will be given with respect to a schematic
construction of the position indicator 2 with reference to FIG. 2. FIG. 2
is a cross sectional view taken along line A-A' of the position indicator
2 shown in FIG. 1.

[0054] The position indicator 2 serves to indicate a position for the
position detector 1 by using an electromagnetic induction system. The
position indicator 2 has a resonance circuit which enters into resonance
with an electric wave having a specific frequency and transmitted thereto
from the position detector 1. The position indicator 2 transmits a
resonance signal detected by the resonance circuit to the position
detector 1, thereby indicating a position for the position detector 1.

[0055] As shown in FIG. 2, the position indicator 2 is constructed so as
to include a case 11 showing a concrete example of a chassis, a core body
12, a position indicating coil 13, a variable capacitor 15, a ferrite
core 16, and a printed wiring board 17.

[0056] The case 11 is formed as an external packaging portion of the
position indicator 2. The case 11 has a bottomed cylindrical shape whose
one end is closed. The case 11 is composed of a first case 18 and a
second case 19 which are assembled, and coupled with the first case 18
and the second case 19 being axially superposed on each other. The first
case 18 has approximately a conical shape at one end side in an axial
direction, and has an opening portion 18a at a tip of that one end side.
The other end of the first case 18 in the axial direction is open.

[0057] The second case 19 has a cylindrical shape whose one end in the
axial direction is open and whose other end is closed. The first case 18
and the second case 19 are disposed on the same axis line, and are fixed
to each other by using a firmly fixing section such as an adhesive agent
or fixing screws. The printed wiring board 17 having electronic parts or
components mounted thereto is firmly fixed to the second case 19 by using
a firmly fixing section such as an adhesive agent or fixing screws. The
ferrite core 16 is accommodated in the first case 18.

[0058] The ferrite core 16, for example, has a cylindrical shape, and a
core body 12 is inserted into a cylindrical hole 16a of the ferrite core
16. An indication portion 12a of the core body 12 protrudes from one end
side in the axial direction of the ferrite core 16. In addition, a
position indicating coil 13 composing a resonance circuit is wound around
the outer periphery of the ferrite core 16 to be mounted thereto. Both
ends (not shown) of the position indicating coil 13 are electrically
connected to opposite terminals of corresponding one of the electronic
parts or components firmly fixed to the printed wiring board 17,
respectively. Electronic parts or components composing the resonance
circuit are mounted to the printed wiring board 17.

[0059] The core body 12 is made from approximately a rod-like member, and
is accommodated in the case 11 along the axial direction of the case 11.
The core body 12 is composed of the indication portion 12a, and an axis
portion 12b. In this case, the indication portion 12a has a role of a pen
tip at one end of the core body 12 in the axial direction. The axis
portion 12b is continuously formed from the indication portion 12a. The
indication portion 12a is formed approximately in a conical shape. The
indication portion 12a protrudes from the opening portion 18a of the
first case 18 toward the outside when the core body 12 is accommodated in
the case 11. The variable capacitor 15 is mounted to the other end of the
axis portion 12b in the axial direction.

[Variable Capacitor 15]

[0060] Next, the variable capacitor 15 of the position detector 1
composing an embodiment of the input device will be described with
reference to FIG. 3 to FIGS. 6A and 6B. FIG. 3 is an exploded perspective
view of the variable capacitor 15. FIGS. 4A and 4B are a top plan view
and a bottom plan view, respectively, of a conductive elastic member 15c
of the variable capacitor 15. In addition, FIG. 5 is a cross sectional
view of the variable capacitor 15 portion when both of the printed wiring
board 17 and the core body 12 are mounted to the variable capacitor 15.
Also, FIGS. 6A and 6B are cross sectional views explaining an example of
joining between the printed wiring board 17 and a dielectric 15a.

[0061] The variable capacitor 15 is a capacitor whose capacitance value is
changed so as to correspond to a pressure (pen pressure) applied to the
position indicator 2. The variable capacitor 15 detects the pen pressure
applied to the core body 12 as a corresponding change in capacitance
value, and thus serves as a pen pressure detecting portion of the
position indicator 2.

[0062] As shown in FIG. 3, the variable capacitor 15 is composed of the
dielectric 15a, a spacer (spacing member) 15b, and the conductive elastic
member 15c. The dielectric 15a, the space (spacing member) 15b, and the
conductive elastic member 15c are held between the printed wiring board
17 and the core body 12, to be used as the variable capacitor 15 of the
position indicator 2.

[0063] The dielectric 15a is formed in a columnar shape having a first
surface portion 15a1 and a second surface portion 15a2 opposite to each
other. In the illustrated embodiment, for example, the dielectric 15a is
2.95 mm in outer diameter, 1 mm in thickness, and 160 pF (permittivity:
4,000 F/m) in capacitance value. Here, the unit, mm, means a millimeter,
the unit, pF, means a picofarad, and the unit, F/m, means a meter per
farad.

[0064] It is noted that numerical values of the dielectric 15a provided
above are examples only, and thus various numerical values can be adopted
in accordance with the size of the position indicator 2 having the
variable capacitor 15 mounted thereto, the size of the printed wiring
board 17, and the like. In one embodiment, the second surface portion
15a2 of the dielectric 15a is subjected to mirror polishing, thereby
increasing the degree of adhesion to a dielectric contacting portion 15cX
of the conductive elastic member 15c (see FIG. 5), which will be
described later. In addition, various kinds of materials such as ceramics
and plastic can be used as the material for the dielectric 15a as long as
they meet the conditions of the capacitance, the permittivity, and the
like.

[0065] The spacer (spacing member) 15b is formed in a ring-like (annular)
shape. An inner diameter of the spacer 15b is smaller than a diameter of
the dielectric 15a and an outer diameter of the spacer 15b is larger than
the diameter of the dielectric 15a and is slightly smaller than an inner
diameter of the conductive elastic member 15c, which will be described
later, into which the spacer is accommodated. Adoption of such a
construction can prevent position shift of the spacer 15b within the
conductive elastic member 15c.

[0066] When the spacer 15b is made to correspond to the dielectric 15a
having the size exemplified above, the spacer 15b is set to be about 2.6
mm in inner diameter, and about 4.3 mm in outer diameter. In addition,
the thickness of the spacer 15b is set equal to or smaller than 125
μm, for example. Of course, the numerical values shown here are
examples only, and thus suitable material values can be adopted based on
the size and the like of the dielectric 15a. In addition, although
various kinds of insulators can be used as the material for the spacer
15b, the spacer 15b may be formed from a Polyethylene Terephthalate (PET)
film or a polyimide film, for example.

[0067] A holder portion 15c1 for a board and the like, and the core body
holder portion 15c2, are formed integrally with each other, by using a
conductive rubber, into the conductive elastic member 15c.

[0068] The holder portion 15c1 for a board and the like is a cylindrical
portion which has an opening portion having a diameter slightly larger
than the outer diameter of the spacer 15b, and which is provided with a
holding hole (accommodating portion) 15ch for a board and the like having
a predetermined depth while maintaining an area of the opening portion.
The spacer 15b, the dielectric 15a, and a terminal portion of the printed
wiring board 17 are accommodated in order from the lower side in the
holding hole 15ch for a board and the like to be held therein. It is
noted that a side of the holder portion 15c1 for a board and the like
opposite to the opening portion thereof is provided with a closed bottom
surface. This bottom surface composes the dielectric contacting portion
15cX, which is configured to contact the second surface portion 15a2 of
the dielectric 15a (see FIG. 5).

[0069] In addition, as shown in FIG. 3, a paired groove portions 15ck
composing a board coupling portion are provided in respective positions
facing each other of the outer periphery of the holding hole 15ch for a
board and the like of the holder portion 15c1 for a board and the like.
That is to say, as shown in a top plan view of the conductive elastic
member 15c of FIG. 4A, a construction is adopted such that the paired
groove portions 15ck composing the board coupling portion into which the
printed wiring board 17 is inserted are provided in the respective
positions facing each other of the opening portion of the holding hole
15ch for a board and the like of the holder portion 15c1 for a board and
the like.

[0070] A depth of each of the paired groove portions 15ck is set slightly
shallower (shorter) than that of the holding hole 15ch for a board and
the like (see FIG. 5). In addition, a width, w, of each of the paired
groove portions 15ck shown in FIG. 4A is set slightly narrower than a
thickness of the printed wiring board 17 inserted into the paired grooves
15ck. As a result, the printed wiring board 17 inserted into the paired
grooves 15ck is held by the paired grooves 15ck, and the printed wiring
board 17 is prevented from being easily detached from the holder portion
15c1 for a board and the like of the conductive elastic member 15c. Also,
although details will be described later, a lead piece (terminal portion)
provided in the printed wiring board 17 and the conductive elastic member
15c can be electrically connected to each other.

[0071] In addition, the holder portion 15c1 for a board and the like has a
shape as shown in FIG. 4A, in which outer peripheral portions in a
direction (in a vertical direction in FIG. 4A) intersecting with a
diameter direction connecting the paired groove portions 15ck are cut
away. Adoption of such a shape results in that the conductive elastic
member 15c, which is hard to roll and is easy to handle, can be formed
without wastefully using a conductive rubber.

[0072] On the other hand, the core body holder 15c2 is provided in such a
way that a (closed) bottom surface thereof is flush with the bottom
surface of the holder portion 15c1 for a board and the like. The core
body holder portion 15c2 is provided in such a way that an outer diameter
thereof is smaller than that of the holder portion 15c1 for a board and
the like, and a center of the bottom surface of the holder portion 15c1
for a board and the like, and a center of the bottom surface of the core
body holder 15c2 agree with each other.

[0073] The core body holder 15c2 is a cylindrical portion which has an
opening portion having a diameter slightly smaller than an outer diameter
of the axis portion 12b of the core body 12 and which is provided with a
core body holding hole (core body coupling portion) 15 cp having a
predetermined depth while maintaining an area of the opening portion. As
shown in FIG. 3, the axis portion 12b of the core body 12 is inserted
into the core body holding hole 15cp to be held.

[0074] In addition, as shown in the bottom plan view of the conductive
elastic member 15c of FIG. 4B, a construction is adopted such that paired
slit portions (cut portions) 15cs are provided in respective positions
facing each other of the opening portion of the core body holding hole
15cp of the core body holder portion 15c2. A depth of each of the paired
slit portions 15cs is set slightly shallower (shorter) than that of the
core body holding hole 15cp. Provision of the paired slit portions 15cs
results in that it is easy to insert the core body 12 into the core body
holding hole 15cp.

[0075] It is noted that the conductive rubber composing the conductive
elastic member 15c is a synthetic rubber with which a conductive particle
such as a carbon particle or a silver particle is mixed, and is a
material having the flexibility and the elasticity as well as the
conductivity. In general, conductive rubber is classified into one of two
types: a rubber of a type in which an electrical resistance value depends
on a pressure, that is, a rubber (pressure-sensitive rubber) of a type
having a tendency such that a resistance value becomes small as a
depressing force applied is larger, and a rubber (narrow conductive
rubber) of a type in which an electrical resistance value does not depend
on a pressure. Any of the two types of rubbers can be used as the
material composing the conductive elastic member 15c.

[0076] Although the phrases such as flexibility and elasticity are the
terms which are normally used interchangeably with each other, these
phrases can be defined as follows. Flexibility is a property capable of
being bent, or a property capable of being pliant. Thus, flexibility
means that a material can be deformed when a depressing force is applied
thereto, and can be restored back to the original state when the
depressing force is removed. In this case, whether or not a size of the
material itself is changed with respect to (along) the depressing
direction is not relevant. On the other hand, elasticity means that a
size of a material itself is reduced along a depressing direction when a
depressing force is applied to the material, and the material can be
returned back to the original state when the depressing force is removed.
In this case, whether or not the material itself is bent with respect to
the depressing direction is not relevant. Therefore, the conductive
elastic member 15c (having flexibility) in the embodiment can be bent or
contracted when the pressure is applied thereto and can be restored back
to the original state when the pressure is removed.

[0077] As described above with reference to FIG. 3, in the variable
capacitor 15 in the embodiment of the input device, both of the
dielectric 15a and the spacer 15b are accommodated in the holding hole
15ch for a board and the like provided in the holder portion 15c1 for a
board and the like of the conductive elastic member 15c. Also, the
dielectric 15a, the spacer 15b, and the conductive elastic member 15c are
held between the printed wiring board 17 and the core body 12, thereby
serving as the variable capacitor 15 of the position indicator 2.

[0078] In an end portion of the printed wiring board 17, connected to (or
received within) the variable capacitor 15 as shown in FIGS. 3 and 5,
each of the two lateral side portions of the end portion is set slightly
longer than a bottom side portion held between the two lateral side
portions of the end portion. As further shown in FIGS. 3 and 5, a first
lead piece (first terminal portion) 17a is provided in the bottom side
portion of the printed wiring board 17, and second lead portions (second
terminal portions) 17b are provided in both of the lateral side portions,
respectively. The first terminal portion 17a and the second terminal
portions 17b are connected to a predetermined circuit portion(s) provided
on the printed wiring board 17 through respective lead lines (not shown).

[0079] The first lead piece 17a of the printed wiring board 17 is
electrically connected to the first surface portion 15a1 of the
dielectric 15a, and the dielectric 15a itself is firmly fixed to the
printed wiring board 17. In this case, the first lead piece 17a of the
printed wiring board 17 and the first surface portion 15a1 of the
dielectric 15a are joined to each other by, for example, using a method
such as a soldering method or a brazing method. As a result, the first
lead piece 17a of the printed wiring board 17, and the first surface
portion 15a1 of the dielectric 15a are electrically connected to each
other, and the dielectric 15a is firmly fixed to the printed wiring board
17.

[0080] It is noted that the soldering method or the brazing method is an
example of the firmly fixing method. Thus, the first lead piece 17a, and
the first surface portion 15a1 of the dielectric 15a may be electrically
connected to each other by using any of various kinds of conductive
adhesive agents, and thus the dielectric 15a may be firmly fixed to the
printed wiring board 17.

[0081] Both of the end portions of the lateral sides of the printed wiring
board 17 are respectively fitted into the paired groove portions (board
coupling portions) facing each other and provided in the outer peripheral
portion of the holding hole 15ch for a board and the like of the holder
portion 15c1 for a board and the like of the conductive elastic member
15c. As a result, as also described above, the second lead pieces 17b
provided in both of the lateral side portions of the printed wiring board
17, respectively, are electrically connected to the conductive elastic
member 15c.

[0082] Specifically, as shown in a cross sectional view of the variable
capacitor 15 portion of FIG. 5, the ring-like spacer 15b is accommodated
in the holding hole 15ch for a board and the like provided in the holder
portion 15c1 for a board and the like of the conductive elastic member
15c so as to contact the bottom surface of the holding hole 15ch for a
board and the like. Above the ring-like spacer 15b, the first surface
portion 15a1 is electrically connected to the first lead piece 17a of the
printed wiring board 17, and also the dielectric 15a firmly fixed to the
printed wiring board 17 is accommodated together with the printed wiring
board 17 from the opening portion of the holding hole 15ch for a board
and the like.

[0083] In this case, both of the lateral side portions provided with the
second lead pieces 17b of the printed wiring board 17, respectively, are
fitted into the paired groove portions (board coupling portions) 15ck
facing each other and provided in the outer peripheral portion of the
holding hole 15ch for a board and the like. As a result, the second lead
pieces 17b provided in both of the lateral side portions of the printed
wiring board 17, respectively, are electrically connected to the
conductive elastic member 15c through the respective groove portions 15ck
composing the board coupling portions.

[0084] In this case, as shown in FIG. 5, the bottom surface portion of the
holding hole 15ch for a board and the like of the holder portion 15c1 for
a board and the like composing the dielectric contacting portion 15cX,
and the second surface portion 15a2 of the dielectric 15a are separated
(spaced) from each other by a thickness of the spacer 15b by the spacer
15b. That is to say, a space 15d is defined between the bottom surface
portion of the holding hole 15ch for a board and the like of the holder
portion 15c1 for a board and the like composing the dielectric contacting
portion 15cX, and the second surface portion 15a2 of the dielectric 15a
by the spacer 15b.

[0085] As shown in FIG. 5, the axis portion 12b of the core body 12 is
fitted into the core body holding hole 15cp of the core body holder
portion 15c2 of the conductive elastic member 15c. It is then supposed
that a depressing force is applied to the dielectric 15a side of the core
body 12 when, for example, the indication portion 12a of the core body 12
is pressed against the detecting portion 4 of the position detector 1.

[0086] In this case, the conductive elastic member 15c has elasticity and
flexibility as well as conductivity. Therefore, the bottom surface
portion (the dielectric contacting portion 15cX) of the holding hole 15ch
for a board and the like of the board holder portion 15c1 is upward
pressed toward the second surface portion 15a2 side of the dielectric 15a
by the core body 12. Also, the application of the depressing force toward
the dielectric 15a by the core body 12 results in that the bottom surface
portion (the dielectric contacting portion 15cX) of the holding hole 15ch
for a board and the like comes in contact with the second surface portion
15a2 of the dielectric 15a.

[0087] When the depressing force applied toward the dielectric 15a side of
the core body 12 is released, the conductive elastic member 15c is
returned back to the original state by the elasticity and flexibility of
the conductive elastic member 15c. As a result, the operation state is
returned back to the state such that the space 15d is defined between the
bottom surface portion (the dielectric contacting portion 15cX) of the
holding hole 15ch for a board and the like, and the second surface
portion 15a2 of the dielectric 15a by the spacer 15b.

[0088] When the depressing force is not applied to the dielectric 15a side
by the core body 12 in such a way, the space 15d is defined between the
bottom surface portion (the dielectric contacting portion 15cX) of the
holding hole 15ch for a board and the like, and the second surface
portion 15a2 of the dielectric 15a, and therefore electrical connection
is not formed.

[0089] However, when the depressing force is applied to the dielectric 15a
side by the core body 12, the bottom surface portion (the dielectric
contacting portion 15cX) of the holding hole 15ch for a board and the
like, and the second surface portion 15a2 of the dielectric 15a come in
contact with each other. In this case, there is formed a connection
system as follows: the first lead piece 17a of the printed wiring board
17→the first surface portion 15a1 of the dielectric 15a→the
second surface portion 15a2 of the dielectric 15a→the dielectric
contacting portion 15cX of the conductive elastic member 15c→the
board coupling portion 15ck of the conductive elastic member
15c→the second terminal portion 17b of the printed wiring board
17. Thus, the variable capacitor 15 is constructed whose electrical
capacitance is changed in accordance with the contact state,
corresponding to the depressing force, between the second surface portion
15a2 of the dielectric 15a, and the dielectric connecting portion 15cX of
the conductive elastic portion 15c in the connection system.

[0090] As shown in FIGS. 3 and 5, the variable capacitor 15 in the
illustrated embodiment can be basically composed of the three parts or
components: the dielectric 15a; the spacer 15b; and the conductive
elastic member 15c. The variable capacitor 15 having a very simple
construction can be realized in this manner.

[0091] It has been described above that the first lead piece 17a of the
printed wiring board 17, and the first surface portion 15a1 of the
dielectric 15a are joined to each other by, for example, using the
soldering method. In the variable capacitor 15 of the embodiment, for the
purpose of reliably and firmly fixing the printed wiring board 17 to the
first surface portion 15a1 of the dielectric 15a, a sample construction
of a connection end of the printed wiring board 17 to (be connected to)
the conductive elastic member 15c is provided and now described.

[0092] In the embodiment as shown in FIG. 6A, a semi-circular through hole
(a cutout portion (or a holding hole) for holding the solder as the
conductive adhesive agent) 17c is provided in the first lead piece 17a
portion of the connection end of the printed wiring board 17, to be
connected to the conductive elastic member 15c. In other words, the
bottom side portion of the printed wiring board 17 is cut into the
semi-circular shape to provide the through hole 17c. As shown in FIG. 6A,
the first lead piece 17a is provided so as to have an arc-like shape
along the outer peripheral portion of the semi-circular through hole 17c.

[0093] As shown in FIG. 6B, the first surface portion 15a1 of the
dielectric 15a is made to come in contact with the through hole 17c
portion of the printed wiring board 17 constructed in such a way, and a
solder 17x as the conductive adhesive agent is caused to flow into the
through hole 17c portion, thereby carrying out the soldering. As a
result, as shown in FIG. 6B, the through hole 17c is filled with the
solder 17x. Also, when the solder 17x portion is solidified, the first
surface portion 15a1 of the dielectric 15a, and the first lead piece 17a
of the printed wiring board 17 are electrically connected to each other
and also the dielectric 15a is firmly fixed to the printed wiring board
17.

[0094] Thus, in the illustrated embodiment, the construction is adopted
such that the through hole 17c is provided in the connection end of the
printed wiring board 17 to be connected to the conductive elastic member
15c, and the arc-like lead piece 17a is provided in the outer peripheral
portion of the through hole 17c. As a result, the first lead piece 17a of
the printed wiring board 17 and the first surface portion 15a1 of the
dielectric 15a can be electrically connected to each other and also the
dielectric 15a can be firmly fixed to the printed wiring board 17.

[0095] It is noted that although the through hole 17c has been described
as being semi-circular here, the present invention is by no means limited
thereto. For example, a through hole having a polygonal shape such as a
triangular shape or a quadrangular shape may be provided, and the first
lead piece may be provided in an outer periphery or edge of the through
hole.

[Precision of Detection of Pen Pressure (Pressure) in Position Indicator
2]

[0096] As described above, the variable capacitor 15 composes the pen
pressure detecting portion in the position indicator 2. Next, a
description will be given regarding the precision in detection of the pen
pressure (pressure) by the variable capacitor 15 of the embodiment
described above.

[0097] FIG. 7 is a graph showing phase-load characteristics of the
variable capacitor 15 with a load applied to the core body 12 on an axis
of abscissa, and a phase (a difference in phase between a transmitted
electric wave and a received electric wave) on an axis of ordinate.

[0098] Although the variable capacitor 15 of the embodiment described
above has a very simple construction, as shown in FIG. 7, the variable
capacitor 15 can detect a load (pressure) of about 10 g. Also, the
variable capacitor 15 can approximately linearly detect the applied load
up to about 100 g with high sensitivity. The applied load above 100 g up
to about 300 g can be suitably detected as well. Although a change in
phase difference against the applied load of 300 g or more becomes small,
since application of a large pen pressure of 300 g or more to the
position indicator 2 is rare, practical utility of the position indicator
2 using the variable capacitor 15 is not compromised at all.

[0099] The phase-load characteristics of the variable capacitor 15 shown
in FIG. 7 are approximately the same as the characteristics of the
position indicator using the conventional variable capacitor described
with reference to FIGS. 21A and 21B, and FIG. 22, for example. Therefore,
although the variable capacitor 15 of the illustrated embodiment is
simple in construction, the variable capacitor 15 maintains the same
performance as compared with the conventional variable capacitor.

[Circuit Configuration of Position Detector 1]

[0100] Next, a description will be given of a concrete circuit
configuration of the position detector 1, for detecting the indicated
position and the pen pressure, by using the position indicator 2
including the variable capacitor 15 described above with reference to
FIG. 8. FIG. 8 is a block diagram, partly in circuit, showing the
position indicator 2 and the position detector 1. The input device is
composed of the position indicator 2 and the position detector 1.

[0101] The position indicator 2 is configured by a resonance circuit 61
composed of the position indicating coil 13, the variable capacitor 15
connected in parallel with the position indicating coil 13, and a
resonance capacitor 60a connected in parallel with the variable capacitor
15 in terms of a circuit configuration. In various embodiments, the
resonance circuit 61 changes its resonance frequency in accordance with a
change in electrical capacitance of the variable capacitor 15, and the
change in resonance frequency is detected as a pen pressure.

[0102] On the other hand, in the position detector 1, an X-axis direction
loop coil group 104a, and a Y-axis direction loop coil group 104b are
laminated and provided, thereby forming a position detecting coil 101.
Each of the X-axis direction loop coil group 104a, and the Y-axis
direction loop coil group 104b is composed of 40 rectangular loop coils,
for example. The rectangular loop coils composing each of the X-axis
direction loop coil group 104a and the Y-axis direction loop coil group
104b are disposed in such a way that they are arranged at equal intervals
to be superposed one upon another.

[0103] The position detector 1 is provided with a selecting circuit 106,
to which both of the X-axis direction loop coil group 104a and the Y-axis
direction loop coil group 104b are connected. The selecting circuit 106
successively selects one loop coil from the X-axis direction loop coil
group 104a and the Y-axis direction loop coil group 104b.

[0104] The position detector 1 is provided with an oscillator 103, a
current driver 105, a switchover connecting circuit 107, a receiving
amplifier 108, a detector 109, a low-pass filter 110, a sample-and-hold
circuit 112, an A/D conversion circuit 113, a synchronous detector 116, a
low-pass filter 117, a sample-and-hold circuit 118, an A/D conversion
circuit 119, and a processing portion 114.

[0105] The oscillator 103 is one which generates an A.C. signal having a
frequency, f0, and supplies the resulting A.C. signal to each of the
current driver 105 and the synchronous detector 116. The current driver
105 converts the A.C. signal supplied thereto from the oscillator 103
into an A.C. current, and sends the resulting A.C. current to the
switchover connecting circuit 107. The switchover connecting circuit 107
switches connection destinations (a transmission side terminal T and a
reception side terminal R), to which the loop coil selected by the
selecting circuit 106 is connected in accordance with the control made by
the processing portion 114, which will be described later. Of the
connection destinations, the current driver 105 is connected to the
transmission side terminal T, and the reception amplifier 108 is
connected to the reception side terminal R.

[0106] An induced voltage generated in the loop coil selected by the
selecting circuit 106 is sent to the reception amplifier 108 through the
selecting circuit 106 and the switchover connecting circuit 107. The
reception amplifier 108 amplifies the induced voltage supplied thereto
from the selected loop coil, and sends the induced voltage thus amplified
to each of the detector 109 and the synchronous detector 116.

[0107] The detector 109 detects the induced voltage generated in the
selected loop coil, that is, the received signal, and sends the received
signal thus detected to the low-pass filter 110. The low-pass filter 110
has a sufficient lower cutoff frequency than the frequency, f0, described
above, converts the output signal from the detector 109 into a D.C.
signal, and sends the resulting D.C. signal to the sample-and-hold
circuit 112. The sample-and-hold circuit 112 holds an analog voltage
value at a predetermined timing of the output signal from the low-pass
filter 110, specifically, at a predetermined timing during a period of
time for reception, and sends the analog voltage to the Analog-to-Digital
(A/D) conversion circuit 113. The A/D conversion circuit 113 converts the
analog output from the sample-and-hold circuit 112 into a digital signal,
and outputs the resulting digital signal to the processing portion 114.

[0108] On the other hand, the synchronous detector 116 detects the output
signal from the reception amplifier 108 synchronously with the A.C.
signal from the oscillator 103, and sends a signal having a level
corresponding to a difference in phase between the output signal and the
A.C. signal to the low-pass filter 117. The low-pass filter 117 has a
sufficiently lower cutoff frequency than the frequency, f0, and converts
the output signal from the synchronous detector 116 into a D.C. signal
and sends the resulting D.C. signal to the sample-and-hold circuit 118.
The sample-and-hold circuit 118 holds an analog voltage value at a
predetermined timing of the output signal from the low-pass filter 117,
and sends the analog voltage to the Analog-to-Digital (A/D) conversion
circuit 119. The A/D conversion circuit 119 converts the analog voltage
from the sample-and-hold circuit 118 into a digital signal, and outputs
the resulting digital signal to the processing portion 114.

[0109] The processing portion 114 controls the operations of the portions
in the position detector 1. In other words, the processing portion 114
controls the selection of the loop coil in the selecting circuit 106, the
switchover of the switchover connecting circuit 107, and the timings of
the sample-and-hold circuits 112 and 118. The processing portion 114
causes the X-axis direction loop group 104a and the Y-axis direction loop
group 104b to transmit the electric wave for a given transmission
duration in accordance with the input signals from the A/D conversion
circuits 113 and 119.

[0110] The induced voltage is generated in each of the loop coils of the
X-axis direction loop group 104a and the Y-axis direction loop group 104b
based on the electric wave transmitted from the position indicator 2. The
processing portion 114 calculates the coordinate values of the indicated
position in the X-axis direction and in the Y-axis direction in
accordance with the level of the voltage value of the induced voltage
generated in corresponding one of the loop coils. In addition, the
processing portion 114 detects the pen pressure in accordance with the
difference in phase between the transmitted electric wave and the
received electric wave.

[0111] Next, an operation of the position detector 1 carried out along a
flow of processing in the processing portion 114 will be described with
reference to FIG. 9. FIG. 9 is a flow chart representing the flow of the
processing in the processing portion 114.

[0112] Firstly, the processing portion 114 successively scans and selects
the loop coils of the X-axis direction loop group 104a (hereinafter, this
successive scan and selection will be referred to as "global scan") (Step
S1).

[0113] Concretely describing the global scan, the processing portion 114
firstly sends information, in accordance with which the first loop coil
of the X-axis direction loop coil group 104a, for example the loop coil
X1, is selected by the selecting circuit 106, and also sends a signal, in
accordance with which the transmission side is selected by the switchover
connecting circuit 107. As a result, a sine wave signal having the
frequency f0 is supplied from the oscillator 103 to the loop coil X1, so
that the loop coil X1 generates the electric wave having the frequency,
f0. At this time, when the position indicator 2 either approaches or
contacts the upper surface of the detecting portion 4 of the position
detector 1, the electric wave generated from the loop coil X1 excites the
resonance circuit 61 having the position indicating coil 13. As a result,
the induced voltage having the frequency f0 is generated in the resonance
circuit 61.

[0114] After the processing portion 114 sends a signal, in accordance with
which the transmission side terminal T is selected by the switchover
connecting circuit 107 for a given period of time, the processing portion
114 sends a signal, in accordance with which the reception side terminal
R is selected by the switchover connecting circuit 107, thereby causing
the electric wave generated from the loop coil X1 to disappear. In this
case, the induced voltage generated in the resonance circuit 61 of the
position indicator 2 having the resonance capacitor 60a and the variable
capacitor 15 gradually attenuates correspondingly, so that the resonance
circuit 61 transmits the electric wave. The electric wave reversely
excites the loop coil X1 described above, thereby causing the loop coil
X1 to generate the induced voltage.

[0115] After the processing portion 114 sends a signal, in accordance with
which the reception side terminal R is selected by the switchover
connecting circuit 107 for a given period of time, the processing portion
114 sends information, in accordance with which the selecting circuit 106
is caused to select the second loop coil from the X-axis direction loop
group 104a, for example the loop coil X2, to be connected to the
switchover connecting circuit 107. After that, the processing portion 114
sends a signal, in accordance with which the transmission side terminal T
is selected by the switchover connecting circuit 107, thereby carrying
out the same transmission and reception of the electric wave as those in
the foregoing.

[0116] After that, the processing portion 114 executes the same processing
as that of the foregoing, whereby the loop coils from the third to 40-th
loop coils of the X-axis direction loop coil group 104a, for example the
loop coils X3 to X40, are successively scanned and selected. As a result,
the transmission and reception of the electric wave are carried out in
the loop coils X3 to X40 in order.

[0117] It is noted that in the processing in Step S1, the processing
portion 114 may suitably limit the loop coils to be selected such as
every other loop coil or one in every two loop coils. In addition, the
transmission and reception of the electric wave for one loop coil may be
carried out plural times. Moreover, although the transmission time for
each of the loop coils need to be the same, and the reception time for
each of the loop coils need to be the same, the transmission time and the
reception time need not be identical to each other.

[0118] The induced voltage generated in the loop coil of the X-axis
direction loop coil group 104a for the period of time for reception
described above, that is, the A.C. received signal, is detected by the
detector 109 to be converted into a D.C. signal and smoothed in the
low-pass filter 110. The resulting D.C. signal is held at the
predetermined timing by the sample-and-hold circuit 112, and is then sent
as a voltage value to the processing portion 114 through the A/D
conversion circuit 113.

[0119] FIGS. 10A to 10D show an example of waveforms in the portions in
the X-axis global scanning operation (Step S1 in FIG. 9) described above.
FIG. 10A shows the waveforms of the electric wave transmitted from the
position detecting coil 101. FIG. 10B shows the waveforms of the induced
voltage generated in the resonance circuit 61, FIG. 10C shows the
waveforms of the received signal received by the position detector 1, and
FIG. 10D shows the waveforms of the output signal from the
sample-and-hold circuit 112.

[0120] Here, a level of the output signal from the sample-and-hold circuit
112 is a value depending on a distance between the position indicator 2
and the loop coil. For this reason, the processing portion 114 determines
whether or not a maximum value of the level of the output signal from the
sample-and-hold circuit 112 is equal to or larger than a given value
previously set (Step S2), thereby determining whether or not a height of
the position indicator 2 falls within an effective read height of the
position detector 1.

[0121] When it is determined in the processing in Step S2 that the maximum
value of the level of the output signal from the sample-and-hold circuit
112 is not equal to or larger than the given value previously set, that
is, the height of the position indicator 2 does not fall within the
effective read height of the position detector 1 (NO in Step S2), the
processing portion 114 returns the operation back to the processing in
Step S1.

[0122] On the other hand, when it is determined in the processing in Step
S2 that the height of the position indicator 2 falls within the effective
read height of the position detector 1 (YES in Step S2), the processing
portion 114 extracts the loop coil from which the maximum value is
obtained (hereinafter referred to as "a peak coil") from the loop coils
X1 to X40, and stores a number of the peak coil ("X7" in this case) (Step
S3).

[0123] Next, the processing portion 114 successively scans and selects
(global scan) the loop coils of the Y-axis direction loop coil group 104b
(Step S4), and carries out the transmission and reception of the electric
waves in the loop coils of the Y-axis direction loop coil group 104b.

[0124] FIGS. 11A to 11D show an example of waveforms in the portions in a
Y-axis global scanning operation. Here, the signals shown in waveforms in
FIGS. 11A to 11D are the same signals as those shown in FIGS. 10A to 10D,
respectively.

[0125] Next, the processing portion 114 extracts the loop coil from which
the maximum value is obtained (hereinafter referred to as "a peak coil")
of the loop coils Y1 to Y40, and stores a number of the peak coil ("Y5"
in this case) (Step S5).

[0126] Next, the processing portion 114 carries out the transmission and
reception of the electric waves for a predetermined number of X loop
coils adjacent to the X peak coil, for example, five loop coils with the
peak coil of the X-axis direction loop coil group 104a as a center. In
the transmission and reception of each of the electric waves, when the
electric wave is transmitted, that is, when the transmission side
terminal T is selected in the switchover connecting circuit 107, the
processing portion 114 usually selects the peak coil ("the loop coil X7"
in this case). On the other hand, when the electric wave is received,
that is, when the reception side terminal R is selected in the switchover
connecting circuit 107, the processing portion 114 successively scans and
selects (sector scan) the loop coils (the five loop coils in this case)
in the ascending order in number (or in the descending order in number)
(Step S6).

[0127] When the X-axis sector scanning operation has been ended, the
processing portion 114 carries out the transmission and reception of the
electric waves for a predetermined number of Y loop coils adjacent to the
Y peak coil, for example, five loop coils with the peak coil of the
Y-axis direction loop coil group 104a as a center. In the transmission
and reception of each of the electric waves, when the electric wave is
transmitted, that is, when the transmission side terminal T is selected
in the switchover connecting circuit 107, the processing portion 114
usually selects the peak coil ("the loop coil Y5" in this case). On the
other hand, when the electric wave is received, that is, when the
reception side terminal R is selected in the switchover connecting
circuit 107, the processing portion 114 successively scans and selects
(sector scan) the loop coils (the five loop coils in this case) in the
ascending order in number (or in the descending order in number) (Step
S7).

[0128] FIGS. 12A to 12D show an example of waveforms in the portions in
the X-axis sector scanning operation and the Y-axis sector scanning
operation. Here, the signals shown in FIGS. 12A to 12D are the same
signals as those shown in FIGS. 10A to 10D, respectively.

[0129] When the Y-axis sector scanning operation has been ended, the
processing portion 114 determines whether or not each of maximum values
of the induced voltages obtained in the two processing operations in
Steps S6 and S7, respectively, is equal to or larger than a given value
previously set (Step S8), thereby determining whether or not the height
of the position indicator 2 falls within the effective read height of the
position detector 1.

[0130] When it is determined in the processing in Step S8 that the maximum
value of the level of the output signal from the sample-and-hold circuit
112 is not equal to or larger than the given value previously set, that
is, the height of the position indicator 2 does not fall within the
effective read height of the position detector 1 (NO in Step S8), the
processing portion 114 returns the operation back to the processing in
Step S1.

[0131] On the other hand, when it is determined in the processing that the
height of the position indicator 2 falls within the effective read height
of the position detector 1 (YES in Step S8), the processing portion 114
extracts the peak coil in the X-axis direction and the peak coil in the
Y-axis direction from which the maximum induced voltages are obtained,
respectively, and stores numbers of the respective peak coils (Step S9).

[0132] Next, the processing portion 114 extracts plural induced voltages,
for example, three induced voltages in the descending order in level
whenever the X-axis direction sector scan and the Y-axis direction sector
scan are carried out, thereby obtaining the coordinate values in the
X-axis direction and in the Y-axis direction of the position indicated by
the position indicator 2 in accordance with these signals (Step S10). The
coordinate values in the X-axis direction and in the Y-axis direction can
be calculated by carrying out the well-known coordinate calculation, as
described in Japanese Patent No. 2,131,145 commonly assigned as the
present application.

[0133] Next, the processing portion 114 detects the pen pressure from the
level of the signal corresponding to the difference in phase between the
transmitted electric wave and the received electric wave (Step S11).
Hereinafter, the processing portion 114 repetitively executes the six
processing operations in Steps S6 to S11 as long as the height of the
position indicator 2 falls within the effective read height. On the other
hand, if it is determined that the height of the position indicator 2
does not fall within the effective read height, the processing portion
114 returns the operation back to the processing in Step S1.

[0134] This way, with the position detector 1, the position of the
position indicator 2 approaching the position detector 1 can be detected
by the processing portion 114. In addition, the phase of the signal
received is detected, thereby making it possible to obtain the
information on the value of the pen pressure of the position indicator 2.

[Another Configurations of Position Indicator 2]

[0135] Next, a description will be given with respect to another
configuration of the position indicator 2 using the variable capacitor 15
of the embodiment described above according to the present invention.
FIG. 13 is a circuit diagram showing another configuration (second
configuration) of the resonance circuit provided in the position
indicator 2. The resonance circuit 62 having this configuration is
composed of the position indicating coil 13 and the variable capacitor
15. In the resonance circuit 61 having the first configuration (refer to
FIG. 8), the variable capacitor 15 and the resonance capacitor 60a are
connected in parallel with each other, thereby configuring the parallel
resonance circuit. However, the resonance circuit of the position
indicator 2, as shown in FIG. 13, can also be configured by using the
variable capacitor 15 as the capacitor.

[0136] Next, another configuration of a position indicator will be
described with reference to FIG. 14. FIG. 14 is a circuit diagram showing
another configuration of a position indicator 2A. It is noted that in a
description which will be given with reference to FIG. 14, portions
corresponding to those shown in FIG. 8 are designated by the same
reference numerals or symbols, respectively, and a detailed description
is omitted here for the sake of simplicity.

[0137] The position indicator 2A includes a resonance circuit 121 which
resonates with the electric wave having the frequency, f0, and sent from
the position detecting coil 101 (refer to FIG. 8) provided in the
position detector 1. The resonance circuit 121 is composed of the
position indicating coil 13 and the resonance capacitor 60a. In addition,
an Integrated Circuit (IC) 122 manufactured by using the well-known
Complementary Metal Oxide Semiconductor (CMOS) is disposed on a printed
circuit board of the position indicator 2A. The CMOS IC 122 is driven by
a drive power source composed of a diode 123 and a capacitor 124.

[0138] An anode terminal of the diode 123 is connected to the resonance
circuit 121. An A.C. voltage which is generated in the resonance circuit
121 in accordance with an excitation signal supplied from the position
detecting coil 101 is applied to the diode 123. The A.C. voltage is
smoothed by both of the diode 123 and the capacitor 124 and is converted
into a D.C. voltage to be used as a drive power source of the CMOS IC
122. In addition, a signal generated in the resonance circuit 121 is
supplied to the CMOS IC 122 as well through the capacitor 125. The CMOS
IC 122 generates both of a clock signal, synchronously with which the
transmission and reception of the signal are carried out between the
position indicator 2A and the position detector 1, and a clock signal,
synchronously with which the pen pressure is detected in accordance with
a signal supplied thereto through the capacitor 125.

[0139] As described above, the electrical capacitance of the variable
capacitor 15 is changed in accordance with the pen pressure applied to
the core body 12 of the position detector 2 (refer to FIG. 2). The
variable capacitor 15 is connected to a resistor (not shown), thereby
configuring a time constant circuit. Therefore, when the electrical
capacitance of the variable capacitor 15 is changed in accordance with
the pen pressure, a time constant of the time constant circuit is changed
accordingly. The time constant is converted into a pen pressure value
having a predetermined number of bits, for example, 8 bits in the CMOS IC
122.

[0140] The pen pressure data (8-bit pen pressure value) obtained in such a
way is outputted 1 bit by 1 bit from the CMOS IC 122 synchronously with
the above clock signal, synchronously with which the transmission and
reception of the signal between the position detector 1 and the position
indicator 2A are carried out. The CMOS IC 122 controls the switching
between an ON state and an OFF state of the switch 60b connected in
parallel with the resonance circuit 121 in accordance with the pen
pressure data thus outputted. Therefore, when the switch 60b is held in
the OFF state, the position detector 1 detects the signal sent thereto
from the position indicator 2A. On the other hand, when the switch 60b is
held in the ON state, since the resonance circuit 121 is short-circuited,
the signal sent from the position indicator 2A cannot be detected by the
position detector 1.

[0141] As a result, the position detector 1 transmits the excitation
signal in accordance with which the electric power is supplied from the
position detecting coil 101 to the position indicator 2A for a given
period of time. After that, the position detector 1 detects the signal
sent thereto from the position indicator 2A, thereby making it possible
to obtain the pen pressure applied to the core body 12.

[Other Constructions of Variable Capacitor 15]

[0142] Next, other constructions of the variable capacitor 15 will be
described with reference to FIGS. 15A and 15B to FIG. 17. FIGS. 15A and
15B are respectively a cross sectional view showing another construction
of the variable capacitor 15, and a top plan view showing a construction
of the conductive electric portion 15c of the variable capacitor 15 shown
in FIG. 15A. FIG. 16 is a cross sectional view showing still another
construction of the variable capacitor 15. Also, FIG. 17 is a cross
sectional view showing yet another construction of the variable capacitor
15. The variable capacitor 15 in the embodiment of the input device
described above is described as being composed of the dielectric 15a, the
ring-like spacer 15b, and the conductive elastic member 15c. However, the
construction can be further simplified so as not to require the ring-like
spacer 15b in the variable capacitor 15. It is noted that in FIGS. 15A
and 15B to FIG. 17, portions having the same constructions as those of
the variable capacitor 15 described mainly with reference to FIG. 3 to
FIGS. 6A and 6B are designated by the same reference numerals or symbols,
respectively, and detailed descriptions thereof are omitted here for the
sake of simplicity.

[0143] A variable capacitor 15(1) shown in FIGS. 15A and 15B is such that
an insulator portion 15x is provided on the bottom surface of the holding
hole 15ch for a board and the like of the holder portion 15c1 for a board
and the like instead of the ring-like spacer 15b. In other words, as
shown in the top plan view of the conductive elastic member 15c of FIG.
15B, the insulator portion 15x is provided in a portion, indicated by
slant lines, of the bottom surface of the holding hole 15ch for a board
and the like.

[0144] Any of various kinds of insulators may be provided in the portion,
indicated by the slant lines, of the bottom surface of the holding hole
15ch for a board and the like by carrying out evaporation, fusion,
application or the like, or plural protrusions made of any suitable
insulator may be provided in the portion, indicated by the slant lines,
of the bottom surface of the holding hole 15ch for a board and the like,
thereby making it possible to form the insulator portion 15x. The
insulator portion 15x is formed on the bottom surface of the holding hole
15ch for a board and the like of the holder portion 15c1 for a board and
the like in such a way, which makes it unnecessary to accommodate the
spacer 15b in the holding hole 15ch for a board and the like.

[0145] A variable capacitor 15(2) shown in FIG. 16 is such that both of
the lateral side portions 17d of the printed wiring board 17 are formed
so as to protrude (downwardly in FIG. 16) relative to the dielectric 15a,
which is firmly fixed to the bottom side portion of the printed wiring
board 17 (via the solder 17x). As a result, the dielectric 15a firmly
fixed to the bottom side portion of the printed wiring board 17 is spaced
(above) from the bottom surface (the dielectric contacting portion 15cX)
of the holding hole 15ch for a board and the like by both of the lateral
side portions 17c of the printed wiring board 17. In other words, the
space 15d can be provided between the second surface portion 15a2 of the
dielectric 15a and the dielectric contacting portion 15cX.

[0146] In a variable capacitor 15(3) shown in FIG. 17, both of the printed
wiring board 17 and the dielectric 15a are formed so as to have the same
constructions as those of the corresponding portions of the embodiment
described with reference to FIGS. 6A and 6B, and the like. However, the
holding hole 15ch for a board and the like is formed so as to be
different in shape from the corresponding portion of the embodiment
described with reference to FIGS. 6A and 6B, and the like. Specifically,
as shown in FIG. 17, each of the groove portions 15ck into which the
printed wiring board 17 is fitted is made shallow. As a result, the
dielectric 15a firmly fixed to the printed wiring board 17 is spaced
(above) from the bottom surface (the dielectric contacting portion 15cX)
of the holding hole 15ch for a board and the like. In other words, the
space 15d can be provided between the second surface portion 15a2 of the
dielectric 15a and the dielectric contacting portion 15cX.

[0147] As shown in FIGS. 16 and 17, the second surface portion 15a2 of the
dielectric 1a and the bottom surface (the dielectric contacting portion
15cX) of the holding hole 15ch for a board and the like are spaced from
each other to provide the space 15d, thereby making it possible to make
the use of the spacer 15b unnecessary.

[0148] However, to ensure that the second surface portion 15a2 of the
dielectric 15a and the bottom surface (the dielectric contacting portion
15cX) of the holding hole 15ch for a board and the like come in contact
with each other uniformly in accordance with the depressing force applied
to the core body 12, it is preferable either to use the spacer 15b or to
provide the insulator portion 15x. That is, it is preferable to construct
the variable capacitor either like the variable capacitor 15 described
with reference to FIG. 3 to FIGS. 6A and 6B, or like the variable
capacitor 15(1) described with reference to FIGS. 15A and 15B.

[0149] It is noted that the portion of the printed wiring board 17
connected to the conductive elastic member 15c need not be constructed in
the form of one sheet of board, but, for example, may be constructed as a
combination of multiple boards that are crossed, thereby making it
possible to provide the same state as that in the case where the spacer
15b is provided.

[Other Constructions of Conductive Elastic Member 15c]

[0150] In addition, the conductive elastic member 15c is also by no means
limited to the member described above, and thus the conductive elastic
member 15c can be variously improved. FIGS. 18A and 18B are a top plan
view and a bottom plan view, respectively, each showing another
construction of the conductive elastic member 15c. FIGS. 19A and 19B are
a top plan view and a transverse cross sectional view, respectively, each
showing still another construction of the conductive elastic member 15c.
It is noted that in FIGS. 18A and 18B and FIGS. 19A and 19B, portions
which have the same constructions as those in the case of the variable
capacitor 15 mainly described with reference FIG. 3 to FIGS. 6A and 6B
are designated by the same reference numerals or symbols, respectively,
and thus detailed descriptions thereof are omitted here for the sake of
simplicity.

[0151] A conductive elastic material 15c(1) shown in FIGS. 18A and 18B is
basically formed in the same manner as that in the case of the conductive
elastic material 15c described with reference to FIGS. 4A and 4B.
However, each of the groove portions 15ck provided in positions facing
each other of the outer periphery of the holding hole 15ch for a board
and the like of the holder portion 15c1 for a board and the like is
different in shape from that shown in FIG. 4A. In addition, the core body
holding hole 15cp of the core body holder portion 15c2 is also different
in shape from that shown in FIG. 4B.

[0152] Specifically, as shown in the top plan view of the conductive
elastic member 15c(1) of FIG. 18A, paired protrusions P1 are provided in
respective positions facing each other in each of the groove portions
15ck provided in the respective positions facing each other of the paired
outer periphery of the holding hole 15ch for a board and the like. Each
of the protrusions P1 is formed in rod-like shape so as to extend from
the upper end to the lower end of the groove portion 15ck.

[0153] A pair of protrusions P1 is provided such that, when the portions
of the printed wiring board 17 having the second lead pieces 17b are
inserted into the groove portions 15ck, respectively, each of the second
lead piece 17b portions can be more firmly held between the paired
protrusions P1. Therefore, the second lead pieces 17b and the conductive
elastic member 15c(1) can be electrically connected more relatively. In
addition, the printed wiring board 17 mounted to the conductive elastic
member 15c(1) can be prevented from being detached from the conductive
elastic member 15c(1).

[0154] In addition, as shown in the bottom plan view of the conductive
elastic member 15c(1) of FIG. 18B, the core body holding hole 15cp is not
provided with any of the slit portions 15cs, and instead, three
protrusions P2 are provided inside the core body holding hole 15cp. Each
of the three protrusions P2 is formed in rod-like shape so as to extend
from the upper end to the lower end of the core body holding hole 15cp.

[0155] The three protrusions P2 are provided such that the core body 12
inserted into the core body holding hole 15cp can be more firmly held by
the three protrusions P2, and the core body 12 can be reliably held by
the core body holding hole 15cp. In other words, the core body 12 can be
prevented from being detached from the core body holding hole 15cp.

[0156] A conductive elastic member 15c(2) shown in FIGS. 19A and 19B is
composed of the holder portion 15c1 for a board and the like, and the
core body holder portion 15c2 similarly to the case of the conductive
elastic member 15c described above with reference to FIGS. 4A and 4B. In
the conductive elastic member 15c(2) shown in FIGS. 19A and 19B,
similarly to the case of the conductive elastic member 15c described
above with reference to FIGS. 4A and 4B, the holder portion 15c1 for a
board and the like is provided with the holding hole 15ch for a board and
the like, and the core body holder portion 15c2 is provided with the core
body holding hole 15cp.

[0157] However, in the conductive elastic member 15c(2) shown in FIGS. 19A
and 19B, as shown in the top plan view of FIG. 19A, an opening portion of
the holding hole 15ch for a board and the like is provided with a
saw-tooth stopper, and is also provided with cover portions KU and KD for
holding the printed wiring board 17 inserted thereinto between them. FIG.
19B is a cross sectional view of the conductive elastic member 15c(2)
when viewed in the direction of an arrow "a" in FIG. 19A. As shown in
FIG. 19B, the holding hole 15ch for a board and the like is provided
inside the holder portion 15c1 for a board and the like. However, a
construction is adopted such that the cover portions KU and KD are
provided in the upper portion of the holder portion 15c1 for a board and
the like so as to close the opening portion of the holding hole 15ch for
a board and the like.

[0158] When the printed wiring board 17, to which both of the spacer 15b
and the dielectric 15a are firmly fixed, is intended to be accommodated
in the holding hole 15ch for a board and the like of the conductive
elastic member 15c(2) in this case, as indicated by the two arrows shown
in FIG. 19A, the cover portions KU and KD are pushed open to expose the
opening portion of the holding hole 15ch for a board and the like. After
the printed wiring board 17, to which both of the spacer 15b and the
dielectric 15a were firmly fixed, has been accommodated in the holding
hole 15ch for a board and the like, the cover portions KU and KD are
closed. As a result, the printed wiring board 17 thus accommodated is
held by the saw-tooth stopper of the cover portions KU and KD, thereby
making it possible to prevent the printed wiring board 17 from being
detached from the conductive elastic member 15c(2).

[Another Construction of Core Body Holder Portion 15c2]

[0159] Next, another construction of the core body holder portion 15c2
will be described with reference to FIG. 20. FIG. 20 is a cross sectional
view showing the other construction of the core body holder portion 15c2.
The core body holder portion 15c2 of the embodiment described above has
the cylindrical core body holding portion 15cp (refer to FIG. 3) in order
to insert and hold the axis portion 12b of the core body 12 into the core
body holder portion 15c2. In this embodiment, when the pen drops with the
pen tip down, the core body holder portion 15c2 may be damaged due to the
shock in some cases. In order to address this situation, in the other
construction of the core body holder portion 15c2 shown in FIG. 20, for
the purpose of softening the shock caused by dropping of the pen to
thereby prevent damage to the core body holder portion 15c2, a connection
cap 20 is provided between the axis portion 12b of the core body 12 and
the core body holder portion 15c2. Additional provision of the connection
cap 20 results in that the core body holder portion 15c2 can be prevented
from being damaged by the shock caused by dropping of the pen.

EFFECTS OF THE EMBODIMENTS

[0160] As set forth hereinabove, according to various embodiments of the
present invention, the variable capacitor 15 having the performance equal
to that of the conventional variable capacitor can be realized by
provision of the dielectric 15a, the spacer 15b, and the conductive
elastic member 15c. In addition, it is also possible to construct the
variable capacitors 15(1), 15(2), 15(3), etc. each not using the spacer
15b.

[0161] As a result, it is possible to realize a variable capacitor with a
dramatically reduced number of parts or components, as compared with the
case of the conventional variable capacitor. Therefore, it is possible to
realize a variable capacitor, which has a reduced number of parts or
components and which can be very simply manufactured. These effects make
it possible to largely reduce the cost of the variable capacitor. It is
also possible to realize a position indicator using the variable
capacitor, and an input device using the position indicator, which are
further useful in reducing the cost of the position indicator and the
input device.

[Others]

[0162] Although in the embodiments described above, the conductive elastic
member 15c has been described as including both of the holder portion
15c1 for a board and the like, and the core body holder portion 15c2, the
present invention is by no means limited thereto. For example, when the
core body 12 is held movably in the axis direction within the first case
18 as shown in FIG. 2 by a mechanism provided in the first case 18 side,
which ensures that the predetermined position of the conductive elastic
member 15c is depressed by the core body 12, it is unnecessary to provide
the core body holder portion 15c2.

[0163] In addition, as also described above, the shape of the holding hole
15ch for a board and the like of the holder portion 15c1 for a board and
the like can be variously changed. For example, the dielectric 15a can be
formed in a polygonal columnar shape such as a quadrangular columnar
shape, and the spacer 15b can also be formed in a polygonal columnar
shape such as a quadrangular columnar shape so as to correspond to the
shape of the dielectric 15a. In this case, the holding hole 15ch for a
board and the like of the holder portion 15c1 for a board and the like
has a polygonal opening portion, which agrees in shape with the shape of
the dielectric 15a or the spacer 15b.

[0164] In addition, it is also expected to adopt a construction in which
the holding hole 15ch for a board and the like is not provided. In short,
it is only necessary that the variable capacitor 15 is constructed such
that the second lead piece 17b of the printed wiring board 17 is normally
in contact with the conductive elastic member 15c, while only when the
core body 12 is depressed the dielectric contacting portion 15cX (of the
conductive elastic member 15c) comes in contact with the second surface
portion 15a2 of the dielectric 15a connected to the first lead piece 17a
of the printed wiring board 17.

[0165] It is also possible to adopt a configuration such that, in the
position indicator 2, another construction having the variable capacitor
15 is provided on a side opposite to the side where the core body 12 is
provided, such that two core bodies 12 each coupled with a variable
capacitor 15 of the present invention are provided in mirror image. Then,
either end of the position indicator 2 can be used as an input end of the
position indicator. In addition, it is also possible to adopt a similar
configuration having two variable capacitors 15 arranged on both sides of
the position indicator 2 in mirror image, with one side being provided
with the core body 12 to be used as an input end of information, while
the other side being used as a so-called "rubber" eraser for erasing the
inputted information.

[0166] It should be understood by those skilled in the art that various
modifications, combinations, sub-combinations and alterations may occur
depending on design requirements and other factors insofar as they are
within the scope of the appended claims or the equivalents thereof.

Patent applications by Hiroyuki Fujitsuka, Saitama JP

Patent applications by Yasuyuki Fukushima, Saitama JP

Patent applications by WACOM CO., LTD.

Patent applications in class With variable distance between capacitor electrodes

Patent applications in all subclasses With variable distance between capacitor electrodes